Ensure that the AF_UNIX socket pair has at least 65k of buffer space

Ensure that the AF_UNIX socket pair has at least 65k of buffer space

Without this change, pinging a lwipovpn client with something like a
3000 byte payload on macOS often fails as the default buffer sizes on
macOS are 2048 for send and 4096 for receive.

Change-Id: Ice015df81543c01094479929f0cb3075ca4f3813
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20240925063016.22532-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg29413.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>